Generally, a transformer includes a frame, a pair of assembled cores, and a primary and a secondary winding coils wound on the frame, wherein the frame has a longitudinal through hole for passing through the cores, the frame also has a winding area outside the through hole for winding leading wires so as to form the primary winding coil and the second winding coil which are separated by an insulating layer and whose winding terminals are respectively wound on the frame. As shown in R. O. C. Patent No. M242839, entitled “Improved Transformer Structure”, it includes a main body, several insulating pieces, a housing and primary and secondary winding coils wound on the main body. Nowadays, the greatest power output of a power supplier can easily achieve one thousand watts and more, which is far exceeding the conventional expect. Therefore, since the power is increased, the size of the element is also enlarged. However, all the elements have to be welded on a circuit board, which has a universal standard in general power supplier, so that the increased power causes the inner space of the power supplier more and more crowded. Furthermore, the current output of the transformer is achieved by utilizing copper foil to electrically connect to the elements on the circuit board, as shown in FIG. 1, in which the pins of the conventional transformer are connected to a capacitor, an IC or other electronic elements through the copper foil for outputting electricity. Since the current conducting capability of a copper foil with an identical thickness is proportion to the width thereof, the higher the output current, the wider the copper foil. However, the copper foils are arranged on the circuit board, so that the more the copper foils, the more space the circuit board has to be left for arranging, thereby causing the arranging space of the circuit board to become less arid less. As shown in FIG. 1, a circuit board 4 has, mounted therein, plural rectification switches 5, ICs 6, or electronic elements, such as, capacitors 71, resistors 72, and diodes 73. Since the conventional transformer 1 needs to arrange several strips of copper foils 2 for outputting, a lot of space will be occupied so as to narrow the available space and complicate the element arrangement. Furthermore, in the conventional transformer 1, the copper winding coil may have a greater loss as the high frequency current passes through, that's because the resistance of the copper wire makes the current only to flow at the surface of the copper wire, so that the utility rate of copper wire reduces, in other words, the copper wire has a greater resistance under high frequency current. Another problem is heat-dispersing. The frame wound by the copper wire is sleeved on the cores, so that the greenhouse effect might be produced, thereby blocking the outward heat-dispersing. Consequently, when mounting the transformer, it needs to utilize the wire arranging space well or the mounting and welding manner has to be improved.